1. Field of the Invention
This invention generally relates to a light guide plate assembly. More particularly, this invention relates to a light guide plate assembly for a backlight module.
2. Description of the Prior Art
Recently, liquid crystal displays are widely used in many display devices such as televisions, computers, laptops, monitors, cell phones, digital cameras, etc. A backlight module provides the liquid crystal display with a uniform light of sufficient brightness, so that the liquid crystal display can display images normally. In general, a light guide plate used in the backlight module directly influences the performance and the assembly cost of the backlight module.
For an edge type backlight module, the light enters from an edge and is transferred by the light guide plate, which exhibits the advantage of thinner thickness. However, due to the restricted amount of light source, the brightness cannot be significantly increased and a local dimming cannot be performed on the images. Therefore, a conventional backlight module 90 with multiple light guide plates 80 shown in FIG. 1 has superiority in thickness and image contrast. However, since the backlight module has multiple light guide plates, in consideration of the manufacture variation of individual light guide plate, the assembly tolerance, and temperature difference, it is possible to form a non-uniform distribution of light caused by bright or dark bands in gaps between the light guide plates. Hence, how to overcome the non-uniform distribution of light is an important issue for the edge type backlight module.
On the other hand, for a direct type backlight module, optical plates including the light guide plate used therein are generally designed to be lager than the display area, so that abnormal regions caused by significant difference between bright and dark areas and non-uniform brightness occurred when the optical plates are too small to meet the requirements of the display can be prevented. However, larger optical plates result in higher expenses on molding tools and higher manufacture cost, which has no economic benefit.